U.S. patent number 10,202,305 [Application Number 15/313,695] was granted by the patent office on 2019-02-12 for substrate equipped with a multilayer comprising a partial metal film, glazing unit, use and process.
This patent grant is currently assigned to SAINT-GOBAIN GLASS FRANCE. The grantee listed for this patent is SAINT-GOBAIN GLASS FRANCE. Invention is credited to Xavier Caillet, Ramzi Jribi, Nicolas Mercadier, Laura Singh.
United States Patent |
10,202,305 |
Caillet , et al. |
February 12, 2019 |
Substrate equipped with a multilayer comprising a partial metal
film, glazing unit, use and process
Abstract
A substrate is coated on one face with a thin-film multilayer
including at least one metal functional film based on silver or
made of silver having a thickness e of between 7 nm and 20 nm
inclusive of these values, and two antireflection coatings each
including at least one antireflection film. The functional film is
placed between the two antireflection coatings. The multilayer
includes an upper discontinuous metal film having a thickness e' of
between 0.5 nm and 5 nm inclusive of these values. The upper
discontinuous metal film is located above the only or last metal
functional film as counted starting from the face.
Inventors: |
Caillet; Xavier (Fontenay sous
Bois, FR), Jribi; Ramzi (Paris, FR), Singh;
Laura (Paris, FR), Mercadier; Nicolas (Paris,
FR) |
Applicant: |
Name |
City |
State |
Country |
Type |
SAINT-GOBAIN GLASS FRANCE |
Courbevoie |
N/A |
FR |
|
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Assignee: |
SAINT-GOBAIN GLASS FRANCE
(Courbevoie, FR)
|
Family
ID: |
51483602 |
Appl.
No.: |
15/313,695 |
Filed: |
May 22, 2015 |
PCT
Filed: |
May 22, 2015 |
PCT No.: |
PCT/FR2015/051354 |
371(c)(1),(2),(4) Date: |
November 23, 2016 |
PCT
Pub. No.: |
WO2015/177480 |
PCT
Pub. Date: |
November 26, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170144927 A1 |
May 25, 2017 |
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Foreign Application Priority Data
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|
|
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May 23, 2014 [FR] |
|
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14 54658 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C03C
17/3626 (20130101); C03C 17/36 (20130101); C03C
17/3649 (20130101); E06B 3/6715 (20130101); C03C
17/3681 (20130101); C03C 17/366 (20130101); C03C
17/3639 (20130101); C03C 17/3644 (20130101); C03C
2217/73 (20130101); E06B 3/67 (20130101); C03C
2217/261 (20130101); C03C 2217/256 (20130101); C03C
2218/156 (20130101); E06B 3/673 (20130101); C03C
2217/216 (20130101); C03C 2217/212 (20130101); C03C
2217/281 (20130101); Y02B 80/22 (20130101) |
Current International
Class: |
C03C
17/36 (20060101); E06B 3/67 (20060101); E06B
3/673 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 998 564 |
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May 2014 |
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FR |
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2014/164674 |
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Oct 2014 |
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WO |
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2014/164695 |
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Oct 2014 |
|
WO |
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Other References
International Search Report dated Aug. 31, 2015 in
PCT/FR2015/051354 filed May 22, 2015. cited by applicant.
|
Primary Examiner: Loney; Donald J
Attorney, Agent or Firm: Oblon, McClelland, Maier &
Neustadt, L.L.P.
Claims
The invention claimed is:
1. A substrate, comprising: a thin-film multilayer coated on one
face of the substrate, the thin-film multilayer comprising at least
one metal functional film based on silver or made of silver having
a thickness e of between 7 nm and 20 nm inclusive of these values,
and two antireflection coatings, said antireflection coatings each
comprising at least one antireflection film, said functional film
being placed between the two antireflection coatings, wherein said
multilayer comprises an upper discontinuous metal film having a
thickness e' of between 0.5 nm and 5 nm inclusive of these values,
said upper discontinuous metal film being located above the only or
last metal functional film as counted starting from said face,
wherein the upper discontinuous metal film is based on silver or
made of silver, and wherein the upper discontinuous metal film is a
discontinuous layer having a surface area occupation factor in the
range of 50% to 98% and in the form of interconnected islands with
uncovered regions between the islands.
2. The substrate as claimed in claim 1, wherein said multilayer
comprises only one upper discontinuous metal film.
3. The substrate as claimed in claim 1, wherein said multilayer
further comprises a lower discontinuous metal film having a
thickness e' of between 0.5 nm and 5 nm inclusive of these values,
said lower discontinuous metal film being located between said face
and the only or first metal functional film as counted starting
from said face.
4. The substrate as claimed in claim 1, wherein said discontinuous
metal film is located directly on an antireflection film having a
refractive index at 550 nm of at least 1.9, and directly under an
antireflection film having a refractive index at 550 nm of at least
1.9, the refractive index of said antireflection film directly
below being identical to the refractive index of said
antireflection film directly above.
5. The substrate as claimed in claim 1, wherein said discontinuous
metal film is located directly on an antireflection film having an
optical thickness at 550 nm comprised between 1 nm and 8 nm
inclusive of these values and directly under an antireflection film
having an optical thickness at 550 nm comprised between 1 nm and 8
nm inclusive of these values.
6. The substrate as claimed in claim 1, wherein said discontinuous
metal film is located directly on an antireflection film having an
optical thickness at 550 nm comprised between 2 nm and 6 nm
inclusive of these values and directly under an antireflection film
having an optical thickness at 550 nm comprised between 2 nm and 6
nm inclusive of these values.
7. The substrate as claimed in claim 1, wherein said antireflection
coating placed under each metal functional film comprises an
antireflection film of middling index made of a material having a
refractive index of between 1.8 and 2.2 at 550 nm.
8. The substrate as claimed in claim 7, wherein said antireflection
film of middling index is oxide-based or the antireflection film of
middling index has a physical thickness of between 5 and 35 nm.
9. The substrate as claimed in claim 1, wherein the antireflection
coating placed between the face and a first or the only metal
functional film comprises an antireflection film of high index made
of a material having a refractive index of between 2.3 and 2.7 at
550 nm.
10. The substrate as claimed in claim 9, wherein said
antireflection film of high index is oxide-based or the
antireflection film of high index has a physical thickness of
between 5 and 25 nm.
11. The substrate as claimed in claim 1, wherein the antireflection
coating placed above a first or the only metal functional film, on
the side opposite the face, comprises an antireflection film of
middling index made of a material having a refractive index of
between 1.8 and 2.2 at 550 nm.
12. The substrate as claimed in claim 11, wherein said
antireflection film of middling index is oxide-based or the
antireflection film of middling index has a physical thickness of
between 5 and 35 nm.
13. A multiple glazing unit, comprising: at least two substrates
that are held together by a frame structure, said glazing unit
separating an exterior space from an interior space, in which at
least one intermediate gas-filled cavity is placed between the two
substrates, at least one of the two substrates being the substrate
as claimed in claim 1.
14. A process, comprising: depositing at least one discontinuous
metal film in a thin-film multilayer that is deposited on the
substrate as claimed in claim 1.
15. The process as claimed in claim 14, wherein two of the
discontinuous metal films are deposited in the thin-film
multilayer.
16. The substrate as claimed in claim 1, wherein the surface area
occupation factor of the upper discontinuous metal film is in the
range of 53% to 83%.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a national stage application of
international application no. PCT/FR2015/051354, filed May 22,
2015, and claims priority to French patent application no. 1454658,
filed May 23, 2014, the contents and disclosure of each of which
are incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
Not Applicable.
INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT
DISC
Not Applicable.
STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINT
INVENTOR
Not Applicable.
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a transparent substrate especially made of
a stiff mineral material such as glass, said substrate being coated
with a thin-film multilayer comprising one or more functional films
able to act on solar radiation and/or long-wavelength infrared
radiation.
The invention more particularly relates to a substrate, especially
a transparent glazing substrate, equipped with a thin-film
multilayer comprising "n" metal functional films, especially
functional films based on silver or a metal alloy containing
silver, and of "(n+1)" antireflection coatings, where n is an
integer .gtoreq.1, in alternation, the or each functional film
being placed between two antireflection coatings. Each
antireflection coating comprises at least one antireflection film,
each coating preferably being composed of a plurality of films, at
least one film of which, or even each film of which, is an
antireflection film. Here, the concept "antireflection film" is
synonymous with the concept "dielectric film"; the concept
"dielectric film" above all being used in contrast to the concept
"metal functional film", the metal nature of such functional films
meaning that they cannot be dielectric.
The invention more particularly relates to the use of such
substrates in the manufacture of thermally insulating and/or
solar-control glazing units. These glazing units may be intended to
be used in buildings or vehicles, especially with a view to
decreasing the need for air conditioning and/or preventing
excessive overheating (what are referred to as "solar-control"
glazing units) and/or to decreasing the amount of energy dissipated
toward the exterior (what are referred to as "low-E" glazing units)
as a result of the continuing increase in the square footage of
glazed areas in buildings and vehicle passenger compartments.
These substrates may in particular be integrated into electronic
devices, the multilayer then possibly being used as an electrode to
conduct a current (lighting device, display device, photovoltaic
panel, electrochromic glazing unit, etc.), or may be integrated
into glazing units having particular functionalities, such as for
example heated glazing units.
Description of the Related Art Including Information Disclosed
Under 37 CFR 1.97 and 1.98
One type of film multilayer known to provide substrates with such
properties is formed with a metal functional film having reflective
properties in the infrared and/or with respect to solar radiation,
especially a metal functional film based on silver or a metal alloy
containing silver or made entirely of silver.
In this type of multilayer, the metal functional film is thus
located between two antireflection dielectric coatings, each of
which in general comprises a plurality of films each of which is
made of an antireflection material--either a nitride (especially
aluminum or silicon nitride) or an oxide.
A blocker coating is however sometimes inserted between one or each
antireflection coating and the metal functional film, the blocker
coating located under the functional film, i.e. on the same side as
the substrate, protecting the functional film during any
high-temperature heat treatments, such as bending and/or tempering
heat treatments, and the blocker coating located on the functional
film, i.e. on the side opposite the substrate, protecting this
layer from possible degradation during the deposition of the upper
antireflection coating and during any high-temperature heat
treatments, such as bending and/or tempering heat treatments.
At the present time, it is generally desired for each metal
functional film to be a complete film, i.e. for the entirety of
their area and the entirety of their thickness to consist of the
metal material in question.
For a given material (silver for example) and under deposition
conditions that are conventional for this material, a complete film
is considered to be obtained by those skilled in the art only once
a certain thickness has been deposited.
The adhesion energy between a complete silver film and
antireflection films is very low, of about the order of 1
J/m.sup.2, and the adhesion energy between two anti-reflection
films is 5 to 9 times higher than that between silver and an
antireflection film. The adhesion energy of a multilayer comprising
at least one functional film made of silver or based on silver is
therefore limited by the low adhesion energy between complete metal
functional films and other materials.
BRIEF SUMMARY OF THE INVENTION
The inventors have studied the possibility of depositing thin-film
multilayers comprising one or more metal films and of making a
single metal functional film or several metal films thinner than
the minimum thickness required to obtain a complete film under the
conditions in question.
The inventors have observed that multilayers comprising a single
metal functional film, this metal functional film being
discontinuous, and multilayers comprising a discontinuous metal
film above the only or last continuous metal functional film of the
multilayer are highly mechanically resistant and indeed, even more
surprisingly, highly chemically resistant.
Furthermore, the inventors have observed that the multilayers thus
produced are transparent (no haze and no iridescence) and of color,
either in transmission or in reflection, similar to that obtained
with multilayers with (a) similar complete metal functional
film(s).
It is thus possible to use the specific range of nonuniform
absorption in the visible of such a discontinuous metal film to
obtain specific absorption effects in certain wavelength ranges and
to neutralize certain color characteristics (color in reflection on
the multilayer side or substrate side in particular).
Regarding the prior art, multilayers comprising three metal
functional films, the first metal functional film of which is
discontinuous and located between the two others, are known from
international patent application WO 2011/123402. This discontinuous
film has a high light absorbance in the visible and it is stated
that deposition of this discontinuous metal film on zinc stannate
rather than zinc oxide increases the light absorbance of the
multilayer, i.e. of the discontinuous metal film, in the visible.
However, light absorbance values are not indicated for examples 1
to 5 and 9 or for counter example 6.
Moreover, integrated values for light transmittance and light
reflectance on the substrate or multilayer side are not indicated;
only the colors after tempering in the L*a*b* system, in reflection
multilayer side, in reflection substrate side and in transmission,
are indicated for coated substrates not incorporated into glazing
units (table 1).
Light transmission (VLT) is indicated for examples 1-4, but only
after the coated substrate has been incorporated into a double
glazing unit; it is on average 40%.
Thus, one subject of the invention in its broadest acceptance, is a
substrate coated on one face with a thin-film multilayer comprising
at least one metal functional film based on silver or made of
silver having a thickness e comprised between 7 nm and 20 nm
inclusive of these values, and two antireflection coatings, said
antireflection coatings each comprising at least one antireflection
film, said functional film being placed between the two
antireflection coatings. Said multilayer comprises a discontinuous
metal film having a thickness e' comprised between 0.5 nm and 5 nm
inclusive of these values, said discontinuous metal film being
located above the only or last metal functional film as counted
starting from said face.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 shows a multilayer containing one functional film and one
discontinuous metal film, the discontinuous metal film being
deposited above the metal functional film.
FIG. 2 shows a multilayer containing one functional film and one
discontinuous metal film, the discontinuous metal film being
deposited under the metal functional film.
FIG. 3 shows a multilayer containing one functional film and two
discontinuous metal films, one discontinuous metal film being
deposited above the metal functional film and one discontinuous
metal film being deposited under the metal functional film.
FIG. 4 shows a double-glazing unit solution incorporating a
multilayer according to the invention.
FIG. 5 shows binary TEM micrographs of, from left to right, a
discontinuous metal film made of silver having a degree of areal
occupation of 53% to 98%.
FIG. 6 shows the light transmittance T.sub.L of examples 1 to 3 as
a function of wavelength .lamda..
FIG. 7 shows the absorption spectrum Ab of examples 1 to 3 as a
function of wavelength .lamda..
FIG. 8 shows the light reflectance R.sub.L of examples 1 to 3 as a
function of wavelength .lamda..
FIG. 9 shows the light transmittance T.sub.L, in %, of the
substrate alone and of examples 5, 5.0, 5.1 and 5.2 as a function
of wavelength .lamda..
FIG. 10 shows the absorption spectrum Ab, in %, of the substrate
alone and of examples 5, 5.0, 5.1 and 5.2 as a function of
wavelength .lamda..
FIG. 11 shows the light reflectance R.sub.G, in %, on the side
opposite the multilayer, of the substrate alone and of examples 5,
5.0, 5.1 and 5.2 as a function of wavelength .lamda..
FIG. 12 shows the light reflectance R.sub.C, in %, on the
multilayer side, of the substrate alone and of examples 5, 5.0, 5.1
and 5.2 as a function of wavelength .lamda..
FIG. 13 shows a multilayer containing two functional films and two
discontinuous metal films, one discontinuous metal film being
deposited under the first metal functional film and one
discontinuous metal film being deposited above the second metal
functional film.
FIG. 14 shows a multilayer containing three functional films and
two discontinuous metal films, one discontinuous metal film being
deposited under the first metal functional film and one
discontinuous metal film being deposited above the third metal
functional film.
DETAILED DESCRIPTION OF THE INVENTION
In one variant, said multilayer comprises only one upper
discontinuous metal film.
In another variant, said multilayer furthermore comprises a lower
discontinuous metal film having a thickness e' comprised between
0.5 nm and 5 nm inclusive of these values, said lower discontinuous
metal film being located between, on the one hand, said face and,
on the other hand, the only or first metal functional film as
counted starting from said face. In this variant, said multilayer
then preferably comprises only two discontinuous metal films,
namely a lower discontinuous metal film and an upper discontinuous
metal film.
According to the invention, the discontinuous metal film thus
deposited, or each discontinuous metal film thus deposited, is a
self-structuring layer the structure of which takes the form of
interconnected islands, the zones between the islands not being
covered.
Said lower discontinuous metal film is preferably located within an
upper antireflection coating; i.e. the last antireflection coating
of the multilayer as counted starting from the substrate, and has
an antireflection film on each side; furthermore, the optional
upper discontinuous metal film is preferably located within a lower
antireflection coating and has an antireflection film on each
side.
In the case where said thin-film multilayer comprises a plurality
of metal functional films, especially a plurality of metal
functional films based on silver or made of silver, preferably none
of the antireflection coatings that are located between two metal
functional films comprises a discontinuous metal film having a
thickness comprised between 0.5 nm and 5 nm inclusive of these
values.
In the context of the invention, the discontinuous metal film, or
each discontinuous metal film may have a thickness e' comprised
between 0.5 nm and 2 nm inclusive of these values.
Preferably, said, or each, discontinuous metal film is located, on
the one hand, directly on an antireflection film having a
refractive index at 550 nm of at least 1.9, and, on the other hand,
directly under an antireflection film having a refractive index at
550 nm of at least 1.9; for said, or each, discontinuous metal
film, the refractive index of said antireflection film directly
below is preferably identical to the refractive index of said
antireflection film directly above.
Preferably, said, or each, discontinuous metal film is moreover
located, on the one hand, directly on an antireflection film having
an optical thickness at 550 nm comprised between 1 nm and 8 nm
inclusive of these values, or even comprised between 2 nm and 6 nm
inclusive of these values, and, on the other hand, directly under
an antireflection film having an optical thickness at 550 nm
comprised between 1 nm and 8 nm inclusive of these values, or even
comprised between 2 nm and 6 nm inclusive of these values.
As this single discontinuous metal film, or most preferably in the
multilayer these two discontinuous metal films, is (are) not
continuous, this allows the antireflection films that surround the
or each discontinuous metal film to make direct contact. The
antireflection films adhere strongly to each other in these zones
of direct contact. Any crack that forms at the weakest interface
i.e. at the interface between the discontinuous metal film and the
adjacent antireflection film, will therefore have to propagate
between the two antireflection films to advance, and will thus
require a higher energy to do so. The adhesion energy of the
multilayer in this location is thus considerably improved, in
particular relative to the case of a continuous absorber film.
In the context of the present invention, the expression
"discontinuous film" will be understood to mean that, if a square
of any size is considered on the surface of the multilayer
according to the invention, then, in this square, the discontinuous
functional film is preferably present only over 50% to 98% of the
area of the square, or even over 53% to 83% of the area of the
square, or even over 63% to 83%, respectively.
The square considered is located in a main portion of the coating;
it is not a question in the context of the invention of producing a
particular border or particular margin that would then be hidden in
the final application.
According to the invention, this type of self-structuring
discontinuous metal film has an adhesion energy higher than that of
a continuous functional film and its optical properties (light
transmittance, light reflectance and emissivity) though worse
remain in ranges that are acceptable for certain specific
applications.
Preferably, said, or each, discontinuous metal film is based on
silver or is made of silver.
Preferably, said, or each, discontinuous metal film does not make
direct contact, neither above nor below, with a continuous metal
film.
It is moreover possible: for said antireflection coating placed
under each metal functional film to comprise an antireflection film
of middling index made of a material having a refractive index
comprised between 1.8 and 2.2 at 550 nm, this antireflection film
of middling index preferably being oxide-based and/or this
antireflection film of middling index preferably having a physical
thickness comprised between 5 and 35 nm; for said antireflection
coating placed between the face and a first or the only metal
functional film to comprise an antireflection film of high index
made of a material having a refractive index comprised between 2.3
and 2.7 at 550 nm, this antireflection film of high index
preferably being oxide-based and/or this antireflection film of
high index preferably having a physical thickness comprised between
5 and 25 nm; for the antireflection coating placed above a first or
the only metal functional film, on the side opposite the face, to
comprise an antireflection film of middling index made of a
material having a refractive index comprised between 1.8 and 2.2 at
550 nm, this antireflection film of middling index preferably being
oxide-based and/or this antireflection film of middling index
preferably having a physical thickness comprised between 5 and 35
nm; for the antireflection coating placed above a first or the only
metal functional film, on the side opposite the face, to comprise
an antireflection film of high index made of a material having a
refractive index comprised between 2.3 and 2.7 at 550 nm, this
antireflection film of high index preferably being oxide-based
and/or this antireflection film of high index preferably having a
physical thickness comprised between 5 and 25 nm; for said
multilayer to comprise two or three metal functional films based on
silver or made of silver each having a thickness e comprised
between 7 nm and 20 nm inclusive of these values and for said
multilayer to furthermore comprise a single upper discontinuous
metal film having a thickness e' comprised between 0.5 nm and 5 nm
inclusive of these values, said upper metal film being located
above the last metal functional film as counted starting from said
face; and for said multilayer to comprise two or three metal
functional films based on silver or made of silver each having a
thickness e comprised between 7 nm and 20 nm inclusive of these
values and for said multilayer to furthermore comprise only two
discontinuous metal films: a lower discontinuous metal film having
a thickness e' comprised between 0.5 nm and 5 nm inclusive of these
values, said lower discontinuous metal film being located between,
on the one hand, said face and, on the other hand, the only or
first metal functional film as counted starting from said face; and
an upper discontinuous metal film having a thickness e' comprised
between 0.5 nm and 5 nm inclusive of these values, said upper
discontinuous metal film being located above the last metal
functional film as counted starting from said face.
The term "coating" will be understood, in the context of the
present invention, to mean that there may be a single film or a
plurality of films of different materials within the coating.
The term "multilayer" is understood to mean a set of thin films
deposited one on top of another, without a mineral substrate
(substrate made of a mineral material such as glass) or an organic
substrate (such as a plastic sheet) interposed therebetween.
As is conventionally the case, when a film is said to be based on a
material or to be material-based what is meant is that the film
mainly consists of this material, i.e. that the chemical element of
the material, or if relevant the product of the material considered
in its stable stoichiometric formula, forms at least 50 at % of the
film in question.
As is conventionally the case, the expression "metal functional
film" designates the deposition of an IR-reflective film that is
continuous.
As is also conventionally the case, the expression "antireflection
film" will, in the context of the present invention, be understood
to mean that, from the point of view of its nature, the material is
a "non-metal", i.e. it is not a metal. In the context of the
invention, this expression designates a material having an n/k
ratio in any wavelength range in the visible (from 380 nm to 780
nm) of 5 or more.
It will be recalled that n designates the real refractive index of
the material at a given wavelength and k represents the imaginary
component of the refractive index at a given wavelength; the ratio
n/k is calculated for a given wavelength.
The refractive index values indicated in the present document are
the values measured at a wavelength of 550 nm, as is conventionally
the case.
According to the invention, said, or each discontinuous metal film
may have a thickness e': 1.0.ltoreq.e'.ltoreq.4.5 nm or even
1.0.ltoreq.e'.ltoreq.4.0 nm; or 2.0.ltoreq.e'.ltoreq.4.5 nm or even
2.0.ltoreq.e'.ltoreq.4.0 nm, deposited on a film based on titanium
dioxide TiO.sub.2; or 1.0.ltoreq.e'.ltoreq.4.5 nm or even
1.0.ltoreq.e'.ltoreq.4.0 nm; or 2.0.ltoreq.e'.ltoreq.4.5 nm or even
2.0.ltoreq.e'.ltoreq.4.0 nm, deposited on a film based on zinc tin
oxide ZnSnO.sub.x; or 1.0.ltoreq.e'.ltoreq.5.0 nm or even
1.0.ltoreq.e'.ltoreq.4.5 nm; or 2.0.ltoreq.e'.ltoreq.5.0 nm or even
2.0.ltoreq.e'.ltoreq.4.5 nm, deposited on a film based on zinc
oxide ZnO; or 1.0.ltoreq.e'.ltoreq.5.0 nm or even
1.0.ltoreq.e'.ltoreq.4.0 nm; or 2.0.ltoreq.e'.ltoreq.5.0 nm or even
2.0.ltoreq.e'.ltoreq.4.0 nm, deposited on a film based on silicon
nitride Si.sub.3N.sub.4.
Preferably, the multilayer according to the invention is deposited
directly on the face of the substrate.
For a multilayer according to the invention comprising a single
continuous metal functional film, this functional film may have a
thickness comprised between 8 and 17 nm, or even between 10 and 15
nm, or even between 12 and 14 nm in order to obtain an effective
low-E multilayer.
In another particular version of the invention, at least one metal
functional film is deposited directly on an under-blocker coating
placed between the functional film and the antireflection coating
subjacent to the functional film and/or at least one functional
film is deposited directly under an over-blocker coating placed
between the functional film and the antireflection coating
superjacent to the functional film and the under-blocker coating
and/or the over-blocker coating comprises a thin film based on
nickel or titanium having a physical thickness comprised between
0.2 nm and 2.5 nm inclusive of these values.
The last film of the superjacent antireflection coating, i.e. the
film furthest from the substrate, may be oxide-based, and is then
preferably deposited in substoichiometric form; it may especially
be based on titanium dioxide (on TiO.sub.x) or based on mixed tin
zinc oxide (on Sn.sub.zZn.sub.yO.sub.x).
The last film (or overcoat) of the multilayer may thus be a
protective film preferably deposited in substoichiometric form.
This film ends up oxidized, stoichiometrically for the most part,
in the multilayer after the deposition.
The invention furthermore relates to a multiple glazing unit
comprising at least two substrates that are held together by a
frame structure, said glazing unit separating an exterior space
from an interior space, in which at least one intermediate
gas-filled cavity is placed between the two substrates, one
substrate being according to the invention.
As a particular variant, the multilayer according to the invention
is positioned on face 4 of a double glazing unit, i.e. on a face of
the glazing unit that is not protected by the intermediate
gas-filled cavity, as the multilayer is particularly resistant.
The glazing unit according to the invention incorporates at least
the substrate bearing the multilayer according to the invention,
optionally associated with at least one other substrate. Each
substrate may be clear or tinted. One of the substrates at east may
in particular be made of bulk-tinted glass. The type of tint chosen
will depend on the light transmittance and/or color that it is
desired for the glazing unit to have once manufactured.
The glazing unit according to the invention may have a laminated
structure, especially associating at east two stiff glass
substrates with at east one thermoplastic polymer sheet, in order
to obtain a glass/thin-film multilayer/sheet(s)/glass/glass sheet
structure. The polymer may especially be based on polyvinyl butyral
PVB, ethylene vinyl acetate EVA, polyethylene terephthalate PET or
polyvinyl chloride PVC.
The invention furthermore relates to the use of a, and preferably
at most two, discontinuous metal film(s) according to the invention
in a multilayer comprising at least one metal functional film based
on silver or made of silver having a thickness e comprised between
7 nm and 20 nm inclusive of these values, and two antireflection
coatings, said antireflection coatings each comprising at least one
antireflection film, said functional film being placed between the
two antireflection coatings, said multilayer furthermore comprising
an upper discontinuous metal film having a thickness e' comprised
between 0.5 nm and 5 nm inclusive of these values, said upper
discontinuous metal film being located above the only or last metal
functional film as counted starting from said face; an optional
other discontinuous metal film being a lower discontinuous metal
film located between, on the one hand, said face and, on the other
hand, the only or first metal functional film as counted starting
from said face and having a thickness e' comprised between 0.5 nm
and 5 nm inclusive of these values.
The invention furthermore relates to a process for depositing a,
and preferably at most two, discontinuous metal film(s) according
to the invention in a multilayer comprising at least one metal
functional film based on silver or made of silver having a
thickness e comprised between 7 nm and 20 nm inclusive of these
values, and two antireflection coatings, said antireflection
coatings each comprising at least one antireflection film, said
functional film being placed between the two antireflection
coatings, said multilayer furthermore comprising an upper
discontinuous metal film having a thickness e' comprised between
0.5 nm and 5 nm inclusive of these values, said upper discontinuous
metal film being located above the only or last metal functional
film as counted starting from said face; an optional other
discontinuous metal film being a lower discontinuous metal film
located between, on the one hand, said face and, on the other hand,
the only or first metal functional film as counted starting from
said face and having a thickness e' comprised between 0.5 nm and 5
nm inclusive of these values.
Advantageously, the present invention thus allows a thin-film
multilayer to be obtained having (deposited on a transparent
substrate) a light transmittance in the visible T.sub.L>50%, a
light reflectance in the visible R.sub.C (multilayer side) lower
than 20% and even lower than 10%, and a relatively neutral color in
transmission and reflection, the emissivity of the coated substrate
being lower than that of the substrate by itself.
Advantageously, the present invention thus allows a thin-film
multilayer to be produced comprising 1, 2, 3, 4 or even more metal
functional films based on silver or made of silver and containing
one, and preferably at most two, discontinuous metal films, so that
the multilayer is highly mechanically resistant and/or highly
chemically resistant.
Details and advantageous features of the invention will become
apparent from the following nonlimiting examples, which are
illustrated in the appended figures, which show:
FIG. 1, a multilayer containing one functional film and one
discontinuous metal film, the discontinuous metal film being
deposited above the metal functional film;
FIG. 2, a multilayer containing one functional film and one
discontinuous metal film, the discontinuous metal film being
deposited under the metal functional film;
FIG. 3, a multilayer containing one functional film and two
discontinuous metal films, one discontinuous metal film being
deposited above the metal functional film and one discontinuous
metal film being deposited under the metal functional film;
FIG. 4, a double-glazing unit solution incorporating a multilayer
according to the invention;
FIG. 5, binary TEM micrographs of, from left to right, a
discontinuous metal film made of silver having a degree of areal
occupation of 53% to 98%;
FIG. 6, the light transmittance T.sub.L (expressed in the form of a
factor ranging from 0 to 1 for values conventionally considered 0
to 100%) of examples 1 to 3 as a function of wavelength
.lamda.;
FIG. 7, the absorption spectrum Ab (expressed in the form of a
factor ranging from 0 to 1 for values conventionally considered 0
to 100%) of examples 1 to 3 as a function of wavelength
.lamda.;
FIG. 8, the light reflectance R.sub.L (expressed in the form of a
factor ranging from 0 to 1 for values conventionally considered 0
to 100%) of examples 1 to 3 as a function of wavelength
.lamda.;
FIG. 9, the light transmittance T.sub.L, in %, of the substrate
alone and of examples 5, 5.0, 5.1 and 5.2 as a function of
wavelength .lamda.;
FIG. 10, the absorption spectrum Ab, in %, of the substrate alone
and of examples 5, 5.0, 5.1 and 5.2 as a function of wavelength
.lamda.;
FIG. 11, the light reflectance R.sub.G, in %, on the side opposite
the multilayer, of the substrate alone and of examples 5, 5.0, 5.1
and 5.2 as a function of wavelength .lamda.;
FIG. 12, the light reflectance R.sub.C, in %, on the multilayer
side, of the substrate alone and of examples 5, 5.0, 5.1 and 5.2 as
a function of wavelength .lamda.;
FIG. 13, a multilayer containing two functional films and two
discontinuous metal films, one discontinuous metal film being
deposited under the first metal functional film and one
discontinuous metal film being deposited above the second metal
functional film; and
FIG. 14 a multilayer containing three functional films and two
discontinuous metal films, one discontinuous metal film being
deposited under the first metal functional film and one
discontinuous metal film being deposited above the third metal
functional film.
FIGS. 1 to 3 illustrate a structure of a one-functional-film
multilayer 34, i.e. of a multilayer containing one functional film,
deposited on a transparent glazing substrate 30 and more precisely
on one face 31 of this substrate 30, in which structure the one
functional film 140, based on silver or a metal alloy containing
silver and preferably made only of silver, is placed between two
antireflection coatings, the subjacent antireflection coating 120
being located under the functional film 140, i.e. on the same side
as the substrate 30, and the subjacent antireflection coating 160
being placed above the functional film 140, i.e. on the side
opposite the substrate 30.
These two antireflection coatings 120, 160 each comprise at least
one antireflection film 128, 168.
Optionally, on the one hand the functional film 140 may be
deposited directly on an under-blocker coating placed between the
subjacent antireflection coating 120 and the functional film 140,
and on the other hand the functional film 140 may be deposited
directly under an over-blocker coating 150 placed between the
functional film 140 and the superjacent antireflection coating
160.
The under- and/or over-blocker films, although deposited in metal
form and presented as being metal films, are in practice oxide
films because their primary function is to oxidize during the
deposition of the multilayer in order to protect the functional
film.
This antireflection coating 160 may terminate with an optional and
in particular oxide-based protective film (not illustrated) that is
especially substoichiometric in oxygen.
When a multilayer containing one functional film is used in a
multiple glazing unit 100 of double glazing unit structure, as
illustrated in FIG. 4, this glazing unit comprises two substrates
10, 30 that are held together by a frame structure 90 and that are
separated from each other by an intermediate gas-filled cavity
15.
The glazing unit separates in this way an exterior space ES from an
interior space IS.
The multilayer according to the invention, because it is highly
mechanically resistant, may be positioned on face 4 (on the sheet
closest the interior of the building with respect to the incident
direction of solar light entering into the building, and on its
face on the interior side).
FIG. 4 illustrates this positioning (the incident direction of
solar light entering into the building being illustrated by the
double arrow) on face 4 of a thin-film multilayer 34 positioned on
an exterior face 31 of the substrate 30 making contact with the
exterior space ES, the other face 29 of the substrate 30 making
contact with the intermediate gas-filled cavity 15.
However, it is also possible to envision, in this double glazing
structure, one of the substrates having a laminated structure;
however, this cannot possibly be a cause for confusion as in such
structures there is no intermediate gas-filled cavity.
A series of seven examples have been produced: example 1 is a
reference example: it is a question of a reference multilayer
containing one functional film and no discontinuous metal films;
example 2 is a comparative example that is based on example 1 and
that furthermore comprises, in the upper part of the multilayer
containing one functional film (i.e. above this functional film,
starting from the substrate), a metal absorber film 167'; example 3
is an example that is based on example 1 and that furthermore
comprises, in the upper part of the multilayer containing one
functional film, an upper discontinuous metal film 167; example 4
is a comparative example that is based on example 1 and that
furthermore comprises, in the lower part of the multilayer
containing one functional film (i.e. between this functional film
and the substrate) an absorber film 123'; example 5 is an example
that is based on example 1 and that furthermore comprises, in the
lower part of the multilayer containing one functional film, a
lower discontinuous metal film 123; example 6 is a comparative
example that is based on example 1 and that furthermore comprises,
in the lower part of the multilayer containing one functional film
(i.e. between this functional film and the substrate) an absorber
film 123', and that furthermore comprises, in the upper part of the
multilayer containing one functional film (i.e. above this
functional film, starting from the substrate) and an absorber film
167'; and example 7 is an example that is based on example 1 and
that furthermore comprises, in the lower part of the multilayer
containing one functional film, a lower 123 discontinuous metal
film, and that furthermore comprises, in the upper part of the
multilayer containing one functional film, an upper discontinuous
metal film 167.
For all the multilayers below, the conditions of deposition of the
films were:
TABLE-US-00001 Deposition Film Target employed pressure Gas
Si.sub.3N.sub.4:Al 92:8 wt % Si:Al 1.5 .times. 10.sup.-3 mbar
Ar/(Ar + N.sub.2) of 45% TiO.sub.2 TiO.sub.2 1.5 .times. 10.sup.-3
mbar Ar/(Ar + O.sub.2) of 45% ZnO ZnO 1.5 .times. 10.sup.-3 mbar
Ar/(Ar + O.sub.2) of 83% NiCr 80:20 wt % Ni:Cr 2 .times. 10.sup.-3
mbar 100% Ar Ag Ag 8 .times. 10.sup.-3 mbar 100% Ar
The films deposited for these examples may thus be classed into
five categories: i--films made of a dielectric/antireflection
material, having an n/k ratio in any wavelength range in the
visible higher than 5: films 121, 121', 128, 162, 168, 169, 169'
made of Si.sub.3N.sub.4:Al, or TiO.sub.2, or ZnO; ii--continuous
metal functional films 140 made of silver, material having
reflective properties in the infrared and/or with respect to solar
radiation; iii--over-blocker films 150 intended to protect the
functional film from a modification of its nature during the
deposition of the multilayer: Ni, NiCr; their influence on the
optical and energetic properties is in general ignored since they
are small in thickness (thickness smaller than or equal to 2 nm);
iv--for examples 3, 5 and 7: discontinuous metal films 123 and/or
167, or DML films, DML standing for discontinuous metal layer; and
v--for comparative examples 2, 4 and 6: metal absorber films 123'
and/or 167' made of titanium; this type of film is a continuous
film.
In all the examples the thin-film multilayer was deposited on a
substrate, G, that consisted of a 4 mm-thick sheet of the clear
soda-lime glass sold under the Planilux brand by SAINT-GOBAIN.
For these multilayers, T.sub.L indicates: the light transmittance
in the visible in %, measured under illuminant D65 at 2.degree.;
a*.sub.T and b*.sub.T indicate the a* and b* coordinates of the
color in transmission in the LAB space measured under illuminant
D65 at 2.degree.; R.sub.G indicates: light reflectance on the glass
side (that surface of the substrate which is opposite that on which
the multilayer is deposited) in the visible in %, measured under
illuminant D64 at 2.degree.; a*.sub.G and b*.sub.G indicate the a*
and b* coordinates of the color in reflection in the LAB space
measured under illuminant D65 at 2.degree. on the side of the
substrate opposite the side coated with the multilayer (face 29);
R.sub.c indicates: light reflectance on the thin-film multilayer
side (surface 31 of the substrate) in the visible in %, measured
under illuminant D65 at 2.degree.; a*.sub.C and b*.sub.C indicate
the a* and b* coordinates of the color in reflection in the LAB
space measured under illuminant D65 at 2.degree. on the coated side
of the substrate (face 31); g indicates the G-factor or solar
factor of a configuration: for examples 1 to 3: the multilayer was
placed on the face 3 of a double glazing unit comprising two 4
mm-thick glass substrates separated by a 16 mm-thick argon-filled
cavity, the substrate bearing the multilayer thus being the second
substrate passed through by incidence of a light; and for examples
4 to 7: the multilayer was placed on the face 2 of a double glazing
unit comprising two 4 mm-thick glass substrates separated by a 16
mm-thick argon-filled cavity, the substrate bearing the multilayer
thus being the first substrate passed through by incidence of a
light.
This factor was determined according to standard EN 410 and
corresponds to the sum of direct energy transmission through the
glazing unit and of secondary heat transfer into the interior.
According to the invention, a discontinuous DML metal film is a
discontinuous film that preferably has a degree of areal occupation
(as a percentage of the area of the layer that is located just
under the discontinuous metal film and that is covered by the
discontinuous metal film) comprised between 50% and 98%.
According to the invention, a discontinuous DML metal film is a
film that preferably mainly comprises (i.e. comprises at least 50
at %) at least one metal chosen from: Ag, Au, Cu, Pt.
According to the invention, a discontinuous DML metal film is a
film that is preferably flanked on each side, above and below, by a
film made of a dielectric/antireflection material, the refractive
index n of which is preferably at least equal to 1.9.
FIG. 5 shows, from left to right: a degree of areal occupation of
53% obtained with a silver thickness of 2 nm; this multilayer
having an emissivity .epsilon.=88.7%; a degree of areal occupation
of 63% obtained with a silver thickness of 3 nm; this multilayer
having an emissivity .epsilon.=49.3%; a degree of areal occupation
of 84% obtained with a silver thickness of 4 nm; this multilayer
having an emissivity .epsilon.=23.9%; and a degree of areal
occupation of 98% obtained with a silver thickness of 5 nm; this
multilayer having an emissivity .epsilon.=15.7%; obtained for a
thin-film multilayer Z having the following structure:
substrate/ZnO/silver DML film/ZnO, each ZnO film (of a refractive
index of n=1.9) having a thickness of 10 nm.
Theoretical calculations show that it is possible to obtain with a
multilayer of the Z type an emissivity .epsilon..sub.Z lower than
that of the substrate alone for a DML silver thickness of 5 nm or
less, i.e. for a degree of areal occupation between 50% and 98%,
but nonetheless higher than that observed.
In the present document, when reference is made to the thickness e
of a DML, it is not a question of the thickness measured in the
zones covered by the DML or an average thickness, but of the
thickness that would be obtained if the film were continuous.
This value may be determined by considering the deposition rate of
the film (or more precisely the run speed of the substrate through
the deposition chamber in which the metal functional film is
deposited) i.e. the amount of material sputtered per unit time, and
the area over which the film is deposited. This thickness is very
practical because it is directly comparable to the thickness of
continuous functional films.
The thickness e' is thus the thickness that would be measured if
the deposited film were continuous.
In practice, if normally, under the magnetron sputtering deposition
conditions in question (very low pressure, composition of the
target, run speed of the substrate, cathode electrical power) the
thickness of the functional film is 10 nm, all that is required to
obtain a functional film of half the thickness, i.e. of 5 nm
thickness, is to decrease the run speed of the substrate by
half.
FIG. 5 shows four binary (black/white) transmission electron
microscope (TEM) micrographs. In the four micrographs in this
figure, the silver is white and the ZnO black.
It was observed that for a multilayer Z of this type adhesion
energy is almost constant for a silver thickness of more than 5 nm:
this energy is comprised between 1.0 and 1.5 J/m.sup.2, which is
quite low.
Table 1 below illustrates the geometric or physical thicknesses
(i.e. not the optical thicknesses) in nanometers of each of the
films of examples 1 to 3, with reference to FIG. 1:
TABLE-US-00002 TABLE 1 Film Ex. 1 Ex. 2 Ex. 3 169 - TiO.sub.2 2 nm
2 nm 2 nm 169' - TiO.sub.2 167' - Ti 1 nm 167 - Ag 1 nm 2 nm 2 nm
168 - Si.sub.3N.sub.4:Al 30 nm 28 nm 28 nm 164 - TiO.sub.2 11 nm 11
nm 11 nm 162 - ZnO 6 nm 6 nm 6 nm 140 - Ag 13 nm 13 nm 13 nm 128 -
ZnO 5 nm 5 nm 5 nm 124 - TiO.sub.2 23 nm 23 nm 23 nm
In examples 1 to 3, the antireflection coating 120 placed between
the face 31 and the only metal functional film 140 comprises an
antireflection coating 124 of high index made of a material having
a refractive index comprised between 2.3 and 2.7 at 550 nm, this
high-index antireflection film 124 preferably having a physical
thickness comprised between 5 and 25 nm.
In examples 1 to 3, the antireflection coating 160 placed above the
only metal functional film 140 comprises an antireflection film 162
of middling index made of a material having a refractive index
comprised between 1.8 and 2.2 at 550 nm, this antireflection film
162 of middling index preferably having a physical thickness
comprised between 5 and 35 nm.
Table 2 below illustrates the physical thicknesses in nanometers of
each of the films of examples 4 and 5, with reference to FIG.
2:
TABLE-US-00003 TABLE 2 Film Ex. 4 Ex. 5 168 - Si.sub.3N.sub.4:Al 40
nm 40 nm 162 - ZnO 5 nm 5 nm 150 - NiCr 0.5 nm 0.5 nm 140 - Ag 13
nm 13 nm 128 - ZnO 5 nm 5 nm 121' - TiO.sub.2 20 nm 20 nm 123' -
NiCr 1 nm 123 - Ag 1 nm 121 - TiO.sub.2 3 nm 3 nm
Table 3 below illustrates the physical thicknesses in nanometers of
each of the films of examples 6 and 7, with reference to FIG.
3:
TABLE-US-00004 TABLE 3 Film Ex. 6 Ex. 7 169 - TiO.sub.2 2 nm 2 nm
167' - Ti 1 m 167 - Ag 1 nm 169' - TiO.sub.2 2 nm 2 nm 168 -
Si.sub.3N.sub.4:Al 28 nm 28 nm 162 - ZnO 5 nm 5 nm 150 - NiCr 0.5
nm 0.5 nm 140 - Ag 13 nm 13 nm 128 - ZnO 5 nm 5 nm 121' - TiO.sub.2
20 nm 20 nm 123' - NiCr 1 nm 123 - Ag 1 nm 121 - TiO.sub.2 3 nm 3
nm
Examples 2, 4 and 6 are comparable to examples 3, 5 and 7,
respectively, because they all comprise a single metal functional
film made of the same material (Ag) and of the same thickness;
these examples are also comparable to example 1 because it also
comprises a single metal functional film made of the same material
(Ag) and of the same thickness; the antireflection coatings are not
identical from one series (examples 2-3 form one series, examples
4-5 form one series and examples 6-7 form one series) to another
because their compositions have been optimized in order to attempt
to obtain the best possible performance.
The following table shows the main optical properties of examples
3, 5 and 7 (comprising one (ex. 3 and 5) or two (ex. 7) DML
film(s)) and allows these properties to be compared with those of
examples 2, 4 and 6, respectively (comprising one (ex. 2 and 4) or
two (ex. 6) Ti absorber film(s) of equivalent thickness to that of
each DML film) and with those of example 1 (which does not comprise
a DML film or an absorber film).
TABLE-US-00005 TABLE 4 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7
T.sub.L (%) 84.3 68.3 70.4 66.8 65.4 46.1 44.3 a*.sub.T -2.02 -3.02
-3.73 -2.4 0.08 -3.32 2.55 b*.sub.T 4.18 1.39 3.48 6.8 -0.4 0.82
-6.81 R.sub.G (%) 9.9 8.52 17.38 12.1 a*.sub.G 0.9 -1.7 0.53 -0.41
b*.sub.G -6.4 -7.1 7.01 -5.09 R.sub.C (%) 8.51 5.90 8.26 13.5 10.3
13.36 6.53 a*.sub.C 2.94 -4.41 -5.39 1.7 2.32 1.39 1.34 b*.sub.C
-12.18 -20.10 -26.10 -16.1 -12.9 -16.33 -31.26 g 0.57 0.61 0.63
0.44 0.46 0.55 0.57
Thus it may be seen that it is possible to produce: a multilayer
containing one metal functional film and a discontinuous metal film
in the upper antireflection coating (ex. 3) that has a solar factor
G higher than that of a multilayer containing one metal functional
film and a metal absorber film in the upper antireflection coating
(ex. 2) while nonetheless having an almost identical light
transmittance in the visible; a multilayer containing one metal
functional film and a discontinuous metal film in the lower
antireflection coating (ex. 5) that has a solar factor G higher
than that of a multilayer containing one metal functional film and
a metal absorber film in the lower antireflection coating (ex. 4)
while nonetheless having an almost identical light transmittance in
the visible; and a multilayer containing one metal functional film
and a discontinuous metal film in the lower antireflection coating
and a discontinuous metal film in the upper antireflection coating
(ex. 7) that has a solar factor G higher than that of a multilayer
containing one metal functional film and a metal absorber film in
the lower antireflection coating and a metal absorber film in the
lower antireflection coating (ex. 6) while nonetheless having an
almost identical light transmittance in the visible.
Furthermore, an improvement in color neutralization was observed,
the color in transmission in particular being less yellow--b*.sub.T
is lower or even negative.
FIGS. 6 to 8 show, for examples 1 to 3 respectively, light
transmittance T.sub.L, absorption Ab and light reflectance on the
multilayer side R.sub.C as a function of wavelength .lamda. (in
nm).
FIG. 6 shows that the multilayer containing a DML film (ex. 3)
allows a light transmittance to be obtained in the visible that is
very close to that obtained with the multilayer containing a metal
absorber film (ex. 2); however, absorption is higher in the far
visible and in the near infrared (from 550 nm to 1000 nm) with
example 3 than with example 2, and the multilayer-side reflectance
is lower in the far visible and in the near infrared (from 550 nm
to 1000 nm) with example 3 than with example 2, thereby allowing in
the end a higher solar factor to be obtained for a given light
transmittance level in the visible.
FIGS. 9 to 12 respectively show, as a function of wavelength
.lamda. (in nm), light transmittance T.sub.L, absorption Ab,
substrate-side light reflectance R.sub.G and multilayer-side light
reflectance R.sub.C, for the substrate G alone, i.e. no films on
either of its faces, and for example 5 and examples 5.0, 5.1 and
5.2, the latter examples being based on example 5; there was only
one difference between each of examples 5.0, 5.1, 5.2 and example
5: the thickness of the DML film was 0 nm in example 5.0 (DML film
absent); the thickness of the DML film was 0.9 nm in example 5.1;
and the thickness of the DML film was 1.2 nm in example 5.2.
These figures show that the presence of the DML film increases
absorption at the expense of light transmittance but that a low
light reflectance is obtained substrate-side and
multilayer-side.
Increasing the nominal DML thickness allows the overall absorption
level and color selectivity to be increased.
These trials in particular show that a discontinuous metal film
having a thickness e' in the range from 0.9 to 1.2 nm is
particularly favorable to the obtainment of a relatively high light
transmittance in the visible (65-68%) at the same time as having a
quite low glass-side light reflectance (6-7%) and a quite low
multilayer-side light reflectance (8-9%).
Furthermore, low b*.sub.c values (of about -15), low b*.sub.G
values (of about -10) and low a*.sub.T values (of about -1.0 to
+0.3) were obtained.
In all the above examples, the and/or each discontinuous metal film
123, 167 is located, on the one hand, directly on an antireflection
film 121', 169' having a refractive index at 550 nm of at least 1.9
and even, in this case, of 2.3 (because TiO.sub.2 was used), and on
the other hand, directly under an antireflection film 121, 169
having a refractive index at 550 nm of at least 1.9 and even, in
this case, of 2.3 (because TiO.sub.2 was used), the refractive
index of said antireflection film 121', 169' directly below here
being identical to the refractive index of said antireflection film
121, 169 directly above.
Trials have shown that it is possible to use silicon nitride
(Si.sub.3N.sub.4:Al) of refractive index at 550 nm of 2.0 instead
of TiO.sub.2 for the films 121, 121', 169, 169'.
It has been observed that the and/or each DML film 123, 167 has an
absorption spectrum such that the absorption is relatively low in
the wavelength range from 380 nm to 480 nm, relative to the
absorption in the wavelength range from 480 nm to 780 nm.
It has moreover been observed that it is not necessary for the
and/or each DML film 123, 167 to make direct contact, neither
below, nor above, with a continuous metal film, as in this case the
specific absorption spectrum of the DML film merges with the
(relatively constant in the visible i.e. from 380 nm to 780 nm)
absorption spectrum of the continuous metal film with which it
makes contact.
FIGS. 13 and 14 illustrate the structure of a multilayer 35
containing two functional films and the structure of a multilayer
36 containing three functional films, respectively, said
multilayers being deposited on a transparent glazing substrate 30
and more precisely on one face 31 of said substrate 30.
Each of the functional films 140, 180, 220, which are preferably
mainly based on silver or a metal alloy containing silver and more
preferably made only of silver, is placed between two
antireflection coatings, namely a subjacent antireflection coating
120, 160, 200 located below each functional film 140, 180, 220,
i.e. on the same side as the substrate 30, and a superjacent
antireflection coating 160, 200, 240 placed above each functional
film 140, 180, 220, i.e. on the side opposite the substrate 30.
Each antireflection coating 120, 160, 200, 240 contains at least
one antireflection film 128, 168, 208, 248.
FIG. 3 shows a multilayer 34 that comprises a metal functional film
140, preferably a film based mainly on silver or made of silver,
that is the only metal functional film of the multilayer, and two
discontinuous metal films 123, 167, one of which is located
between, on the one hand, said face 31 and, on the other hand, the
metal functional film 140, starting from said face 31, the other
being located above the metal functional film 140, starting from
said face 31.
FIG. 13 illustrates a similar solution for a multilayer 35
containing two functional films. This multilayer 35 comprises two
metal functional films 140, 180, which films are preferably based
mainly on silver or made of silver, and two discontinuous metal
films 123, 167, one of which is located between, on the one hand,
said face 31 and, on the other hand, the first metal functional
film 140, starting from said face 31, and the other of which is
located above the second metal functional film 180, starting from
said face 31.
FIG. 14 illustrates a similar solution for a multilayer 36
containing three functional films. This multilayer 36 comprises
three metal functional films 140, 180, 220, which are preferably
based mainly on silver or made of silver, and two discontinuous
metal films 123, 167, one of which is located between, on the one
hand, said face 31 and, on the other hand, the first metal
functional film 140, starting from said face 31, and the other of
which is located above the third metal functional film 220,
starting from said face 31.
These three double-DML configurations allow multilayers exhibiting
a low light reflectance but having a more neutral color in
transmission and reflection than would be the case if the
discontinuous metal films were both replaced in each configuration
with a metal absorber film, to be obtained.
With regard to the structures in FIGS. 13 and 14, it is possible to
provide a single lower discontinuous metal film 123 that will then
be located between, on the one hand, said face 31 and, on the other
hand, the first metal functional film 140 as counted starting from
said face 31, or a single upper discontinuous metal film 167 that
will then be located above the last metal functional film 180, 220
as counted starting from said face 31.
Mainly using one (or more) noble metals such as Ag, Au, Pt or Cu
allows a DML to be simply and reliably deposited by magnetron
sputtering as this process allows the growth of islands to be
controlled; specifically, the selective absorption in particular
results from the plasmonic character of the metal, which is made
possible by an islanded structure.
The present invention is described above by way of example. It will
be understood that a person of ordinary skill in the art will be
able to produce various variants of the invention without however
departing from the scope of the patent such as defined by the
claims.
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